Lane keeping assistant apparatus

Abstract

A lane keeping assistant apparatus assists steering force when the vehicle is about to deviate from the lane to provide the driver with improved steering feeling. The lane keeping assistant apparatus includes traveling position detecting means for detecting a traveling position of a vehicle; lane center locating means for locating the width center of a lane on which the vehicle is traveling; lateral deviation amount calculating means for calculating a lateral deviation amount of the traveling position relative to the width center; a power source for providing a steering unit of the vehicle with an assist torque; assist torque determining means for determining the assist torque to be provided by the power source based on the lateral deviation amount, wherein the assist torque determining means gradually reduces the assist torque if the lateral deviation amount is being reduced by a driver's steering operation.

Description

BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] The present invention relates to a lane keeping assistant apparatus which assists steering force when the vehicle is about to deviate from the lane (traveling lane) [0003] 2. Description of the Related Art [0004] Conventionally, there has been studied and developed a lane keeping assistant apparatus in which a camera placed in the vehicle acquires an image of the forward of the vehicle; the vehicle lateral position (a lateral deviation amount) relative to the lane is calculated based on the result of image processing such as lane recognition; and a steering operation by the driver is assisted such that the lateral deviation amount is reduced. Some cars already incorporate the lane keeping assistant apparatus therein. In the below description, the lane represents a lane on which the vehicle is traveling. [0005] Such a conventional lane keeping assistant apparatus generally includes a controller (ECU) which retains a ...

AI Technical Summary

Benefits of technology

[0014] With the lane keeping assistant apparatus, since the assist torque is being gradually reduced when the lateral deviation amount is being reduced by a steering operation of a driver of the vehicle, it is possible to realize fine steering feeling without making the driver discomfort. In addition, the present invention can realize a lane keeping assistant control which values driver's steering operations.

[0016] This configuration can provide finer steering feeling as compared with a setting the assist torque to sharply drop to zero.

[0018] As an additional preferable feature, if the lateral deviation amount is being reduced by a steering operation of the driver, the assist torque determining means may gradually reduce the assist torque in accordance with a predetermined map; and after that, if the lateral deviation amount is not being reduced by a steering operation of the driver while the assist torque determining means is gradually reducing the assist torque, the assist torque determining means may gradually reduce or return the assist torque such that the assist torque becomes a suitable value for the lateral deviation amount.

[0019] These configurations can improve steering feeling of the driver.

[0021] This configuration makes it possible to surely judge the driver's steering operation for emergency avoidance during the normal assist control. Discontinuing the normal assist control under such a situation prevents the driver's steering operation to be obstructed, so that improved steering feeling can be provided to the driver and at the same time the vehicle safety can be enhanced.

[0022] Setting the predetermined value to be 55 deg / sec can judge the driver's steering operation for emergency avoidance with high accuracy.

Problems solved by technology

If the driver intentionally steers such that the vehicle approaches the width lane center while the lane keeping assistant apparatus is working, the driver may feel discomfort because the assist steering force conversely obstructs the driver's steering operation.

Further, if the white lines on the both side of the vehicle cannot be recognized for some reason while the lane keeping assistant apparatus is working, sudden vanishing of the assist torque that has been acting makes the driver discomfort.

On the other hand, if the white-line recognition that has been impossible becomes possible again, simple application of an assist torque also makes the driver feel discomfort.

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